Recent statistics and a couple of wins announced today seem to indicate Cisco Systems Inc. (Nasdaq: CSCO) has gained back some market share against Juniper Networks Inc. (NYSE: JNPR) in core routers lately.

XO Communications Inc. announced that it's picked the CRS-1 for a core-backbone upgrade involving nine U.S. locations, and Savvis (Nasdaq: SVVS) says it included the CRS-1 in its latest buildout. (See XO Picks CRS-1.)

The XO build, which includes a first phase of 10 CRS-1s that go live this week, is notable, considering the carrier had been using Juniper in the core since 2001, when the M160 and M40 won the job for an OC192 buildout. (See XO Deploys Juniper Routers.) Thanks in part to the telecom crash, XO hasn't needed much upgrading in the IP network since then. Its priority has been the optical backbone, which got updated with Infinera Corp. (Nasdaq: INFN) gear. (See XO Picks Infinera Again.)

Predictably, XO says the Juniper boxes aren't going anywhere. "Juniper will continue to be in our network. This will be an augment," says Don MacNeil, XO's vice president of carrier services.

XO is being vague about why it bypassed Juniper, which has its own T640 and the upcoming T1600 as core options. (See Juniper Attacks Cisco's CRS-1.) "Cisco just made more sense for our business model," MacNeil says.

Considerations included total cost of ownership and some marketing support from Cisco related to XO's enterprise business -- meaning, for example, that Cisco and XO will collaborate in some promotion and training efforts, MacNeil says.

Savvis's case is a bit less of a surprise. Savvis did inherit a Juniper-based backbone upon acquiring Cable & Wireless assets in 2004. (See Savvis Bulks Up.) But in combining its network with C&W's, Savvis decided 18 months ago to go with Cisco, says Ron Dobes, Savvis's vice president of product management. That includes the CRS-1 in the network core and Cisco 1800 and 3800 routers at the customer premises, he explains.

Juniper declined to comment for this story.

The CRS-1 has given Cisco a bit of a comeback against the Juniper T640, which had picked up some market share points earlier this decade. How much ground Cisco has regained is debatable, though.

Cisco says it's got a 61.9 percent market share in core routers, but figures from the Dell'Oro Group put Cisco's share at 56 percent at the end of September, up from 55 percent the previous quarter.

It's true Cisco has rebounded, as its core-router share fell to 54 percent at the end of 2005, says Dell'Oro analyst Shin Umeda. But on average, Cisco and Juniper have been holding steady with core-router share in recent years. "You'd have to go back to the 2002 timeframe" to see figures that are much different, he says.

Cisco was happily disclosing CRS-1 sales figures for a while, citing $110 million in revenues for the quarter ending October 2006, for example. (See Cisco Soars in Q1.) Cisco's stopped doing that, although it continues to say the CRS-1 is doing well.

— Craig Matsumoto, West Coast Editor, Light Reading